This invention relates, in general, to a service valve for a tank and relates more particularly, to a combination safety and service valve for a high-pressure tank.
The combination safety and service valve with which this invention is to be compared is utilized with a high-pressure tank or container such as is used for storing gas for welding. Such a valve commonly includes a body having a sealing portion which is adapted to close an opening in the tank and has another portion which, when the sealing portion closes the tank opening, is positioned externally of the tank. The valve body also defines a flow passage through which the tank is emptied or filled.
Also included in such a combination safety and service valve are safety means for preventing the sudden escape of contents of the high-pressure tank if the external portion of the valve is broken off. Each of such safety means includes a secondary valve positioned internally of the sealing portion for closing the flow passage therein and biasing means for biasing the components of the secondary valve into a condition at which the flow passage is closed. Means are also included for preventing, until the valve breaks, the secondary valve from closing. Examples of prior art combination safety and service valves in which such safety means are utilized are shown and described in U.S. Pat. Nos. 3,930,515 and 4,077,422. Secondary valves described in each of the referenced patents include a cylindrical plug adapted to engage a flat seating surface to thereby close the flow passage.
Commonly, however, the safety means of prior art valves are relatively complicated in construction and are, therefore, relatively costly to manufacture. Furthermore, it is not believed that the dependability of prior art valves, at least those which utilize a cylindrical plug in its secondary valve, is very great. If, for example, the cylindrical plug becomes tilted in relationship to the flat seating surface so that subsequent engagement therebetween does not properly close the flow passage, the safety valve does not prevent the escape of contents of the tank.
Accordingly, an object of the present invention is to provide a new and improved safety and service valve for utilization with a high-pressure tank.
Another object of the present invention is to provide such a safety and service valve which is uncomplicated in structure and which can be easily and economically manufactured.
Still another object of the present invention is to provide such a valve which is highly dependable in operation.